Greenlandman's Galley

The lowest type of profanity and vulgarity.

“In my seafaring days the Greenland sailors were notorious for daring
and their disrespect of speech, prefacing or ending every sentence with
an oath, or some indecent expression. Even in those days [the first
quarter of the nineteenth century] a `Greenlandman's Galley' was
proverbially the lowest in the scale of vulgarity.” —C.Thomson: Autobiography, p. 118.

Too low for even a Greenlandman's Galley.

One whose ideas of decency were degraded below even that of a
Greenland crew.